Treating bibulous paper



Jmyhe substantially increased without matepamit a: the description ofthe invention pro-- improved reeultl. obtained-by coating 4 Oct-1 fzgzawe PATIENT-:1 OFFICE.

chameleon a mm TheDcw my. emu of Michigan mm rm 11-min. sail-amateurrelatel to w .5 It moreiparfldularieconcerm an im- ,Wmtemt'ue,malivarietiee o! hihuious paper, such as.

or the watcrieeivariety, to: ex'amplc,

h itatendencyto disintecrate rapidly under the actionoi'jvipingyet-hende. Varicuemethode 1-0- 'ln'vebempropoeedicroveroomingtbissenoule n w en? latiai'actory. Forexample-binding agent. have incorporated into the paper-to increaeeitepresent invention to a method of treating" paper whereby the wetstrength the'reoi' rially itea beorptive properties. An-f ew me-(tom the.bibuiompapenmcham thntu ed' mkina p per towelin tor example, with awater. loluflon ot a mixture containing-a minor pro- Dcl'tipno! aIater-mluble cellulose ether and a maicrimflcnot a mixture orcompound ctformaldehyde and a mb'hydric alcohol.

' at, and m utiuactory ablorptivityr 1 to one embodimentot theinvention, 50

litofltparte c! an urea-formaldehyde tioh product.

hydric aicohoLiffrhie'eoluticn may then. be alpliedtotowelinz'inanyoithewayrcommcnl'y known in the art, such a; by89mm, brushing, dinpina. or, the like The paper thue coated in thendried in airand heated to a i above 100 C. to, pet up-theurea-formaldehyde resin; A cataLvst,;euch as a trace of phosphoric acid,maybe'addedto thecompositionto i'aciii-' ta'te theaettihgupottMreeimJliter drying,

the paper vmay; be rolled or'iolded as desired.

"is then reatb for above proportime; 0! ingredients give a generally pcoating, abaorptiye ropltranl'th, but these reduce the absorptive prop-15 are secured whenthe coating material; are i the ratio ofapproximately 510 15 parts of 'a water-soluble c l l le ether, 85 to 96parted urea-510mialdehyde condensation productand 70 v Ito100parte0iD01yhydricalcoho1. Thiseolution,

' cults in the formation or aproduct oi exceptione 1 hizhw'et strengthgood abeorptivity, In

' addition-P per coated with asolution oi.the

, type described i not unpleasant to the touch, i. e., is neither harshnor slimy, even when 'wet. I

- r Among suitable-interminable cellulose. ether:

when applied a a coating on 'bihuloue paper, re-

which'may he used according to the invention are various ceiiulosee,such'al dimethylcellwlose; hydroxy aikyl celluloaea, mohairhydrouethylcelluloee: alkali metal salt: carbon-aim ceihnoaee, such asg'ly'cciiate; etc.

- The urea-formaldehyde condensation I .mnthepolvhydn mcondima bemuseum. composition .as a mixture, .or alternativclv,; a

p yhydric Alcohol-modified wee-formaldehyderesin" may ire-used. Thus, Imayuaeeitherga mixture or a simple urea icrmaldehyde condennation asdimethylol urea'with a 40 chemical with urea and formaldeaicoholfsuch asethylene glycol or Ilsceroi. or a resin containing ethylene 8 1cc]. 1;;

' 0! letter. W1 0 1'6 disclosed in I U. 's. no. 2,150,471,: to the 01'In the appended'cleima, the' expreuion poly hydric Alcohol-mm" vurea-formaldehyde reein"ie'intcndedtohelmerietomixtureeoia v lvhydncalcohol and an urea-formaldehyde resin, J as well aa ;to thoeeurea-formaldehyde which have been with polyhydric alcohols during theirmanufacture. 1

Theiomm examples illustrate the principle oi" but are not to becontinued una tn vef j ahd!rom50to100parteoiapolv I Example 1 Teststrips 15 millimeters by 180 millimeters were cut from sheets of anordinary roll of commercial paper toweling manufactured under the tradename Wipemdri and water solutions containing varying proportions ofmethyl cellulose and a glycol-modified urea-formaldehyde resin were thendeposited upon the sample strips at various wet coating thicknesses inthe range between 0.002 and 0.020 inch. All solutions used were of 5 percent by weight concentration. The strips were then air dried, heatedbriefly to 105 C. to set the resin, and conditioned for 24 hours waterat 20 C. was administered to the sheet from a graduated pipette. Therequired time in seconds was noted for the drop to be completelyabsorbed. The end point was taken as the point at which no lightreflection was obtained from the water spot. The wet strength wasdetermined by means of 8. Scott tensile strength tester, test stripsbeing placed between the jaws of the machine and tension being appliedto the strip until breakage occurred. Results obtained indicated that asolution containing approximately 10 parts by weight of methyl cellulosefor each 90 parts by weight of a modified urea-formaldehyde resinimparted the most desirable properties to the toweling. Test stripscoated with this solution had a relatively high degree of absorptivityand satisfactory strength characteristics. In ad'- dition, the surfacesof these strips were not slimy or unpleasant to the touch. However,sample strips of toweling coated with methyl cellulose alone had a slimysurface and a relatively low tensile strength. When a solution ofglycol-modifled urea-formaldehyde resin alone was applied to the teststrips, considerable difficulty in casting was encountered due to thewater-like viscosity of the solution. No improvement was noted in thepaper strength. Results of the tests also indicated that a low viscositycellulose ether imparts greater .absorptivity to the treated paper thandoes a high viscosity cellulose ether when both are employed in thecomposite coating solutions herein claimed.

Example 2 Tests were carried out on test strips prepared in a mannersimilar to those of Example 1 with solutions containing varyingproportions oi. methyl cellulose and unmodified urea-formaldehyde resin.It was found that a test strip coated with a solution containingapproximately 10 parts by weight of methyl cellulose for each 90 partsby weight of urea-formaldehyde had a satisfactory wet strength butunsatisfactory absorptivity. Increasing the methyl cellulose content of'claimed method, the following representative comparative data are given:

wez

Absorptivg i ity. seconds width (average oi (average of several)several) Blbulous paper (blank) 0.6-1.1 Bihulous paper+methyl cellulose0.35-0.52 140-210 Bibulous paper+urea-formaldehyde resins. 1.5-2 120-200Bibulous gaper-i-metgigl oellulose-i-ureaiormalde yde (unm illed) 2-4600-810 Bibulous plaper+mcthyl cellulose-l-ureaormalde yde(unmodltled)+slycol 1.7-2.7 180-260 Bibulous paper-l-methylcellulose-l-glycolmodified urea-formaldehyde 2.2-2.8 70-10.)

In the foregoing the proportions oi components in the treating solutionsemplo were those herein recited.

Other modes of applying the principle of my invention may be employedinstead of those explained, change being made as regards the methodherein disclosed or the materials employed, provided the step or stepsstated by any of the following claims be employed or the product claimedin any of the following claims he obtained.

I therefore particularly point out and distinctly claim as my invention:

1. A method of preparing absorptive paper products of high wet strengthwhich comprises treating a bibulous paper base with a water solutionwhereof the solute comprises a minor proportion of a water solublecellulose ether and a major proportion of a polyhydric alcohol-modifiedureai'ormaldehyde resin, drying the so-coated paper, and heating thepaper to a temperature of approximately to 120 C. to set the resin.

2. A method of preparing absorptive paper products of high wet strengthwhich comprises treating a bibulous paper base with a water s'olutionwhereof the solute comprises from 5 to 40 parts of a water solublecellulose ether, from 50 to parts of an urea-formaldehyde resin modifledwith'from 50 to parts of a polyhydric alcohol, drying the so-calledpaper and heating the paper to a temperature of approximately 90 to C.to set the polyhydric alcohol-modifled a. A method of preparingabsorptive P per products of high wet strength which comprises treatinga bibulous paper base with a'water solution whereof the solute comprisesfrom 5 to 40 parts of water soluble methyl cellulose, 50 to 95 parts oran, urea-formaldehyde condensation product modified with from 50 to 100parts of a polyhydric alcohol, drying the so-coated paper and heatingthe paper to a temperature of apdrying the so-coated paper and heatingthe paper 10 to a temperature of approximately 90 to 120 C.

to let the poly ydric alcohol-modified resin.

6. Bibulous paper or improved wet strength hearing at least asuperficial coating comprising a minor proportion of a water solublecellulose ether and a major proportion of a polyhydric alcohol-modifiedurea-formaldehyde resin.

7. Bibulous paper of improved wet strength bearing at least asuperficial coating comprising a minor proportion of water solublemethyl cellulose and a major proportion of glycol-modifiedurea-formaldehyde resin.

RICHARD D. m.

